Weft straightening apparatus



Feb. 1965 J. D. ROBERTSON ETAL 3,167,

WEFT STRAIGHTENING APPARATUS 3 Sheets-Sheet 1 Filed Jan. 24. 1963 FIG.|

ATTORNEYS Feb. 2, 1965 J. D. ROBERTSON ETAL 3,

WEFT STRAIGHTENING APPARATUS Filed Jan. 24, 1963 3 Sheets-Sheet 2 JOHN D. ROBERTSON WILLIAM P. MCCLEARY ATTO R N EYS Feb. 2, 1965 J. D. ROBERTSON ETAL WEFT STRAIGHIENING APPARATUS Filed Jan. 24, 1963 3 Sheets-Sheet 3 INVENTORS JOHN D. ROBERTSON WILLIAM P MCCLEARY BYW,MZ7AM ATTORNEYS United States Patent 0,

3,167,843 WEFT STRAIGHTENENG APPARATUS John D. Robertson and William P. McCieary, Taunton,

Mass., assignors to Mount Hope Machine Qornpany,

incorporated, Tauntcn, Mass, a corporation of Massachusetts Filed Jan. 24, 1963, Ser. No. 253,684 4 Claims. (Cl. 26-514) This invention relates to an improved weft straightening apparatus for restoring woven textile webs and the like to a desired normal condition in which the weft threads are straight and perpendicular to the Warp threads; more particularly, the improved apparatus provides means for correcting both bowed and skewed distortions of the weft threads. It is a primary object of the invention to provide weft straightening apparatus which is capable of correcting both bowed and skewed distortions by means of a single set of correcting rolls.

Heretofore, it has been known that a skewed distortion, Le, a condition in which the weft threads are straight but are not perpendicular to the warp threads, could be corrected by passing the web over a straight roll which could be tilted about an axis perpendicular to its own rotational axis, and which engages the web in a span between tensioning rolls. Tilting the roll increases the length of travel of one edge of the web over the length of travel of the other edge through the set of rolls, resulting in a differential tension which corrects the distortion. Such a device is disclosed in US. Patent No. 2,343,328, entitled Weft Straightening Method and Apparatus, issued March 7, 1944, to John D. Robertson et al.

It has also been known that a bowed distortion, in which the weft threads are curved from edge to edge of the web, could be corrected by passing the web over a roll having a longitudinally-curved surface, such as a bowed or barrel-shaped roll, which engages the web in a span between tensioning rolls. A bowed roll is preferred because it provides a variable degree of correction; the axle of the bowed roll is rotated about its longitudinal axis to positions in which its curvature causes the length of travel of the central portion of the web to differ from the length of travel of the edges of the web through the set of rolls. The extent of this difference determines the degree of correction. The resulting differential tension between the center and the edges produces the necessary correction. Such an apparatus is shown, for example, in United States Patent No. 2,496,312, entitled Bow Correcting Apparatus, issued February 7, 1950, to John D. Robertson.

We have now discovered that both bowed and skewed abnormalities, and also combinations of these types of distortion, may be corrected by a single set of correcting rolls of a particular construction. An important object of the improved apparatus is the reduction of the number of rolls and ancillary elements required for correction of all types of weft distortion.

In the automatic operation of weft straightening apparatus, various detection means may be utilized for sensing an abnormal weft condition. It has been found desirable to detect the condition of the weft elements in the traveling web by such means immediately after the web leaves the straightening apparatus, and to control the latter in response to detected abnormalities. The unit acts as a servomechanism, applying suificient corrective effect in the straightening apparatus to bring about an essentially distortion-free condition of the goods as they pass through the controlling weft detector. The detection of a developing abnormality should take place with as little delay as possible following the entry into the first correcting element of the straightening apparatus, in

3,351,843 Patented Feb. 2, 1955 order that corrective action may be quickly initiated. The

passage of more than a minimum yardage of defective goods through the apparatus, before corrective action can be initiated, represents waste. Moreover, the shorter the distance between the point on the web where it leaves a correction roll and the point where the residual distortion (if any) is measured by the detectors, the shorter will be the time required for the web to travel this distance. As is well known to those skilled in the art of automatic control, this time is known as process lag, and the minimizing of process lag makes possible a faster-acting control system. This, in turn, minimizes residual error. In terms of the condition of the material being handled, this permits the control to more effectively minimize weft distortion.

In straightening apparatus as known prior to the present invention, however, the necessity for providing separate roll arrays for correcting skewed and bowed abnormalities entails a relatively long path length through the successive correcting mechanisms, prior to reaching the detector. The path length is increased by the tensioning and stabilizing rolls which must engage the web before and after the weft-straightening rolls to permit the latter to operate effectively. A lengthy span between the entry to the first set of correcting rolls and the detector cannot be avoided, and a substantial length of distorted goods must pass through the correcting rolls before the initiation of corrective action. Furthermore, since the process lag is inherently relatively large, control sensitivity must be reduced to avoid instability, with the result that the transient residual error is not rapidly reduced by the action of the control.

It is another object of the invention to reduce the length of travel of a web through weft straightening apparatus, in order that distortions may be detected and corrective action initiated more promptly than heretofore feasible. An additional feature of the invention is its ability to produce a controlled warp-spreading effect in the web.

While the specification concludes with claims distinctly pointing out the subject matter which we regard as our invention, it is believed that a clearer understanding may be gained from the following detailed description of a preferred embodiment thereof, referring to the accompanying drawings, in which:

PEG. 1 is a plan view of the apparatus;

FIG. 2 is a sectional end view taken along line 2--2 in FIG. 1, looking in the direction of the arrows;

FIG. 3 is a sectional end view taken along line 33 in FIG. 1, looking in the direction of the arrows;

FIG. 4 is a diagrammatic view showing a web engaging the weft straightening rolls in their neutral positions; and

FIG. 5 is a view similar to FIG. 4, but showing the weft straightening rolls swung through ninety degrees from their positions of FIG. 4, for bow-correcting action.

Referring to the drawings, the improved weft straightening apparatus includes a pair of longitudinally-curvedsurfaced rolls, which in the preferred embodiment shown comprise bowed rolls 10, 12; a skew-correcting idler roll 14; a tension roll 16; and stabilizing rolls 19, 21 mounted in spaced relation to stabilize and guide a traveling web W through the bowed rolls Ill and 12 under a desired degree of web tension. The idler roll 14 is straight in the embodiment shown, but could be bowed if desired.

Corrective action for removing both bowed and skewed distortions, or any combination thereof, is obtained simultaneously by the interactions of the tensioning and stabilizing rolls with the bowed rolls 10 and 12, and the idler roll 14. The bowed rolls are mounted for independent adjusting movement about each of two axes to secure this corrective action.

The axles 20 and 22 of the rolls 10 and 12, respectively,

are rotatably mounted in flange-mounted ball bearings 24, supported in a frame generally designated 26, so that the plane of curvature of each roll may be adjusted angularly about its longitudinal axis. The frame 26 generally comprises end plates 27 interconnected by a tubular beam 28. Bosses 3G welded on the end plates support the axle 32. of the idler roll 14, so that the idler roll remains parallel to the rectilinear longitudinal axes of the bowed rolls. All of the rolls are preferably of a known type having an axle on which the roll is rotatably mounted by suitable bearings. The bowed rolls are preferably covered with somewhat resilient material such as rubber, while the tension roll 16 and the stabilizing rolls 19, 21 are covered worm is aflixed to a drive shaft 49 rotatably supported in a gear casing 42, preferably by means of thrust bearings (not shown). The gear casing also rotatably mounts the, Worm gears 34 and 36; Rotation of the drive shaft 4%, and thus of the axles of the rolls l and 12, is effected by a motor 44 driving through a gear reduction unit 46 "and a flexible coupling 48, these members being mounted upon a flange 49 attached to the plate 27 The motor is arranged for selective energization for rotation in either direction, bymanual or automaticmeans (not shown), to correct bowed abnormalities in a manner to be described hereinafter.

We have found that one or more longitudinally-curvedsurfaced rolls can be employed in combination with straight tensioning and stabilizing rolls rotatably mounted onfixed bearings to correct skewed as well as bowed weft abnormalities, by mounting the curved-surfaced roll or rolls for angular movement about an axis normal to their rectilinear longitudinal axes (defined by the pivot points at the opposite ends of each curved roll). Ac-

cordingly, theframe 26, carrying the bowed rolls 1% and 12 and the idler roll 14, is rotatably mounted in a base by means of a trunnion 52 welded to the support 28, and received in pillow blocks 54 for rotation about an axis S normal to the longitudinal axes of the bowed rolls and idler roll. supports 56 and 58, which form the base structure with vertical plates 60 and a further tubular support 62. Thrust bearings 64am interposed between the trunnion 52 and the pillow blocks 54 to support end loadings.

The angular position of the frame 26 and the bowed rolls about the axis S is adjustable by means of a reversible motor 66, driving a lead screw 70 through a gear reductionunit 68 and a flexible coupling 72. These elements are supported by a flange 74 formed in one of the base plates 60. The lead screw is threaded in a traveling nut 76, which is pivotally mounted on one frame plate 27. by means of a bracket 7 8.

Referring particularly to FIGS. 1 and 3, it will be seen that angular displacement of the frame 26 about the axis S (exemplified at 26 in FIG. 1) will cause the path length T1 from the tension roll 16 'to'the idler roll 14 and also the path length T2 from the bowed roll 10 to the stabilizing roll 19, to difler at the opposite edge portions of the web, while the path length at the center of the web remains substantially constant. Furthermore, the path lengths T1 and T2 are altered in the same sense at the same edge of the web, as the frame isturned. Tension against-the web is maintained by applying braking torque against the tension roll 16,. by means of a manuallycontrolled or air-controlled'brake (not shown) of a con ventional type. Consequently, one edge portion of the 'web is caused tomove longitudinally with respect to the The pillow blocks are afiixed to tubular I other, and a skewed weft may thereby be brought into a normal perpendicular relationship by applying the proper degree of correction, i.e., by turning the frame 26:to a.

proper angular position about the axis S.

it should be noted that where, as in-the preferred embodiment, two bowed rolls are used, it is necessary that the web be led both to and from these rolls on the same side of a plane defined by their parallel longitudinal axes; otherwise, turning of the frame would lengthen one of the spans T1 or T2, but would shorten the other, and thusat least partially nullify the skew-correcting eifect. In the preferred embodiment, the 'web is caused to enter and leave the array of rolls carried by the frame26,

including the idler roll 14 and the bowed rolls 10 and 12, in substantially opposite directions, making a turn of nearly 180 degrees. The maximumskew-correcting efiect is obtained by this complete reversal of path. The idler roll It establishes this reversal of path and performs the initial pure skew correction, while insuring substantial angular wrap about each of the bowed rolls, without which the latter cannot be fully eifective. If an odd number of bowed rolls is utilized, the idler roll maybe omitted since a reversed path and. adequatewrap are readily v obtained without this member.

Toillustrate the manner of cooperation of the impnoved weft straightening apparatus with automatic weft detector means, such means are shown in FIG. 1, generally designated at 32; The stabilizing rolls 19 and 21 also serve as guide rolls for passing the web through the detector, and are mounted'on a support 84 by means of bosses 86. The support 84 is attached tothe plates 60 of the base 5t by means of bolts 88, or is otherwise secured in predetermined relation to the frame 50, to establish a desired path leading from the weft straightening rolls. The weft detecting means shownyare of .a type enerally disclosed and claimed ina copending United States patent application of Robert O. Gibb, entitled Improved Weft Detecting -Method and Apparatus, Serial No. 253,551, filed January 24, 1963, andfassigned to the assignee of this application: However, it'will be understood that various conventional forms of skew and bow detectors may alternatively be utilized. In the embodiment shown, the web is subjected. to transverse or Weftwise tension by means of pairs of nip-rolls 96, supported in pairsuponbrackets 92 with their axes of rotation turned at an angle to thedirection [of web movement shown by the arrows. The rolls of each nip-roll unit are engaged with the opposite surfacesof the web to induce lateral tension. a

Lateral tension in the web induces incidental distortion of the warp threads which appears as localcurvatures whose characteristics reflect the condition of the weft elements. The slope of the warp elements, i.e., the tangent of the angle formed by the distorted warp elements with respect to the direction of travel of theweb, is a sensitive measure of abnormality of the weft elements. This slope is measured at tWolaterally-spaced points by means of a pair of caster-wheel detectors 82, in each of'which a caster wheel is rotatably mounted in a fork 102, pivotally supported at 104.

The magnitude of the angular displacements of the two detectors is a measure of the magnitude of a weft distortion. The relative senses or angular directions of these displacements-are a measure of the'nature of a distortion;

The arrangement of the weft straightening apparatus is such that skewed and bowed abnormalities may be corrected independently, Without mutual interference, even though both corrections are made by a single set of bowed correcting rolls. This is made possible by the compound adjustability of the rolls about their own longitudinal axes, and about an axis normal to these longitudinal axes. The correction of skewed distortions by the latter adjusting movement has previously been described; the bowcorrecting action will now be described with reference to FIGS. 4 and 5. Referring first to FIG. 4, the bowed rolls and 12 are shown rotated to a neutral position, in which their planes of curvature C1 and C2 are substantially perpendicular to the bisectors B1 and B2 of the angles of wrap of the Web about each roll. In this position, no bow-correcting action takes place, since the path length P of the central portion of the web is substantially equal to the path length E of the edge portions of the web. However, the rolls encounter the web on their concave sides and depart from it on their convex sides, with the result that the web is laterally expanded to some extent by each roll. This expansion is desirable in handling the majority of types of webs, since it overcomes any tendency to wrinkle. It will be understood that if the rolls are reversed 180 degrees, they will tend to contract the web laterally; this is not ordinarily desirable because of the resulting tendency to Wrinkle the web longitudinally. Width control is thus obtained by means of the same apparatus which corrects weft abnormalities. In either case, no bow correction takes place, and a skewed condition may be removed without interference, and without an undesirable inducement of bowed distortion, by the rolls l0 and 12.

The maximum bow-correcting effect can be secured by rotating the rolls 10 and 12 through 90 degrees in either angular direction, one such position being shown in FIG. 5, in which the concave sides of the rolls are turned into the web until the planes of curvature B1 and B2 coincide with the bisectors of the wrap angles C1 and C2. It will be observed that the path length P of the central portion of the web is now substantially less than the path length E of the edges. The enforced lagging of the edge portions results in relative advancement of the central portion, thus tending to correct a bow with a lagging center. The rolls would be turned 180 degrees to obtain maximum correction of a weft bowed with a leading center. Again, the rolls act to correct bow independently of any skew correction which they are adjusted to apply. In intermediate angular positions, the rolls produce varying degrees of bow correction and expansion in combination.

While a preferred embodiment of the invention. has been described by way of illustration, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the true spirit and scope of the invention. The invention may be practiced with one or more bow-correcting rolls, including rolls having longitudinallycurved surfaces such as bowed or barrel-shaped rolls, although the latter are limited to a fixed degree of bow correction. We therefore intend to define the invention in the appended claims without limitation to details of the foregoing embodiment.

We claim:

1. Weft straightening apparatus, comprising:

a base, a frame pivotally mounted on said base for angular adjusting movement about a first axis, and first motive means mounted on said base for pivoting said frame to selected angular positions;

at least one rotatable longitudinally-curved roll having an axle, said axle being mounted in said frame for angular adjusting movement about a longitudinal rectilinear axis thereof which extends normally to said first axis, and second motive means mounted on said frame and drivingly connected for angularly adjusting the axle of said longitudinally-curved roll;

at least two straight rolls rotatably mounted on said base on parallel axes defining a common plane, said plane being spaced from said curved roll, and arranged to guide a traveling Woven web to and from said curved roll;

said common plane being inclined at an angle of substantially less than to said first axis such that in a neutral pivotal position of said frame in which the rectilinear axis of said curved roll is parallel to the axes of said straight rolls the opposite edge portions of a Web engaged with said roll have equal path lengths of travel through the apparatus, and that in skew-correcting angular positions of said frame in which said rectilinear axis is inclined in either sense to the axes of said straight rolls, the opposite edge portions of the web have substantially different path lengths of travel through the apparatus;

the axle of said curved roll being angularly adjustable to at least one neutral position in which the central and edge portions of the web have equal path lengths of travel through the apparatus, and adjustable in either angular sense to bow-correcting positions in which the central and edge portions of web have substantially different path lengths of travel through the apparatus;

and means constructed and arranged for detecting the geometric relation between weft and warp elements in said web and for generating control signals independently responsive to bow and skew components of distortion of said weft elements with respect to said warp elements; said detecting means being operable to actuate said first motive means for pivoting said frame to a skew-correcting position of one sense in response to detection of a skew distortion of that sense, and said second motive means for angularly adjusting said curved roll to a bow-correcting position of one sense in response to detection of a bow distortion of that sense.

2. Weft straightening apparatus as recited in claim 1, in which there are a pair of longitudinally-curved rolls mounted in said frame and having parallel longitudinal rectilinear axes lying in a common plane, said second motive means being drivingly connected with each of the pair for adjusting them in synchronism;

said two straight rolls being spaced on the same side of said last-mentioned common plane whereby angular adjustment of said frame alters the path length of either web edge between said curved rolls and each of said straight rolls in a uniform sense;

and an idler roll mounted in said frame for rotation about an axis parallel to said rectilinear axes of said cur/ed rolls, such that the web may be guided serially over said idler roll and said curved rolls to enter and leave in substantially opposite directions and to have substantial wrap about each of said curved rolls.

3. Weft straightening apparatus, comprising:

a base, a frame pivotally mounted on said base for angular adjusting movement about a first axis, and means mounted on said base for pivoting said frame to selected angular positions;

at least one rotatable longitudinally-curved roll having an axle, said axle being mounted in said frame for angular adjusting movement about a longitudinal rectilinear axis thereof which extends normally to said first axis, and means mounted on said frame for angularly adjusting the axle of said longitudinallycurved roll;

and at least two straight rolls rotatably mounted on said base on parallel axes defining a common plane, said plane being spaced from said curved roll, and arranged to guide a traveling web to and from said curved roll;

said common plane being inclined at an angle of substantially less than 90 to said first axis such that in a neutral position of saidframe in which the rectilinear axis of said curved roll is parallel to the axes of said straight rolls, the opposite edge portions of a Web engaged with said rolls have equal path lengths of travel through the apparatus, and that in skew-correcting positions ofsaid frame in which said rectilinear axis is inclined to the axes of said straight rolls, the opposite edge portions of the web have substantially dififerent path lengths of travel through the apparatus; a

the axle of said longitudinally-curved roll being angularly adjustable to at least one neutral position in and an idler roll mounted in said frame for rotation about an axis parallel to said rectilinear axes of said curved rolls, such that the .web may be guided serially over said idler roll and said curved rolls to enter and leave in substantially opposite directions and to have substantial wrap about each of said curved rolls.

References Cited in the file of this patent which the central and edge portions of the web have UNITED'STATES PATENT equal path lengths of travel through theapparatus, S

and angularly adjustable to bow-correctingpositions 15 1322 h a1 9 1940 in which the'central and edge portions of the web 3 1 12 V Robertson 1950 have substantially different path lengths of travel 1 Robertson 26, 1952 throu h the apparatus, $742,315 Wood Nov. 1, 1955 o 4. Weft straightening apparatus as recited in claim 3, Robertson et a1 June 1957 in which there are a pair of longitudinally-curved'rolls 20" mounted in said frame and having parallel longitudinal FOREIGN PATENTS I rectilinear axes lying in a common plane; 21646 Great a n of 1898 said two straight rolls being spaced on the same side 5 Great r tain of 1913 

3. WEFT STRAIGHTENING APPARATUS, COMPRISING: A BASE, A FRAME PIVOTALLY MOUNTED ON SAID BASE FOR ANGULAR ADJUSTING MOVEMENT ABOUT A FIRST AXIS, AND MEANS MOUNTED ON SAID BASE FOR PIVOTING SAID FRAME TO SELECTED ANGULAR POSITIONS; AT LEAST ONE ROTATABLE LONGITUDINALLY-CURVED ROLL HAVING AN AXLE, SIAD AXLE BEING MOUNTED IN SAID FRAME FOR ANGULAR ADJUSTING MOVEMENT ABOUT A LONGITUDINAL RECTILINEAR AXIS THEREOF WHICH EXTENS NORMALLY TO SAID FIRST AXIS, AND MEANS MOUNTED ON SAID FRAME FOR ANGULARLY ADJUSTING THE AXLE OF SAID LONGITUDINALLYCURVED ROLL; AND AT LEAST TWO STRAIGHT ROLLS ROTATABLY MOUNTED ON SAID BASE ON PARALLEL AXES DEFINING A COMMON PLANE, SAID PLANE BEING SPACED FROM SAID CURVED ROLL, AND ARRANGED TO GUIDE A TRAVELING WEB TO AND FROM SAID CURVED ROLL; 